Roasting furnace construction



April 5, l1932.

D. BAIRD ET Al.

ROASTING FURNACE CONSTRUCTION 2 Sheets-Sheet l Filed May l5, 1930 www@ April 5, 1932- D. BAIRD ET AL ROASTING FURNACE CONSTRUCTION Filed May 13, 1930 2 Sheets-Sheet S'HZ BV MM INVENT Gew eECZ' ATTQRNEYS` Patented Apr. 5, 1932 UNITED STATES PATENT OFFICE '.DUDLEY BAIRD, OF BERKELEY, AND GEORGE E. CONNOLLY, OF OAKLAND, CALIFORNIA, ASSIGNORS, BY MESNE ASSIGNMENTS, TO NICHOLS ENGINEERING AND RESEARCH CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE noAsTING FURNACE CONSTRUCTION Application led May 13,

This invention relates to roasting furnaces such for example as are used for the roasting of sulphur-bearing 'copper ores. Furnaces of this general character are usually constructed with a vertically disposed rotatable shaft which passes through the central portion of a plurality of horizontal substantially circular hearthson which lies the material being treated. Each hearth isprovided with one or more in-ternally cooled rabble arms, each of such arms being secured to the central shaft so as to rotate therewith, and extends horizontally therefrom at a slightV distance above the hearth.

The objects of this invention include the provision of improved rabble arm constructions of the above indicated class, which are relatively inexpensive to construct, repair and maintain, and which are highly efficient and dependable in use.

The foregoing and other and more-specific objects of the invention will readily appear to those skilled in the art, upon consideration of the following description of certain embodiments thereof taken in connection with the accompanying drawings.

The invention consists in such novelV features, arrangements and combinations of parts as may be shown and described in connection with the embodiments of the invention here" disclosed by way of example only.

In the drawings, Fig. 1 is a vertical section of a rabble arm showing a portion of a rotatable central shaft and means for 'attaching v1. uv

'J our improved arm thereto, and also showing adjacent portions of the hearths and furnace; Fig. 2 is a vertical section of another form of rabble arm and the joint forming member whereby it is attached to the rotatable shaft; Fig. 3 is a vertical section similar to Fig. 2 of still another form of rabble arm;

Fig. 4 is a transverse section of the rabble arm taken on the line 4.-4 of Fig. l; and

Fig. 5 is a transverse section of the rabble 1930. serial No. 451,887.

arm and joint forming member taken on the terial on the hearth 13 may drop to another e similar hearth 15 positioned beneath the hearth 13. `The hearth 15 extends closer to the rotatable shaft 12 than does the hearth 13 and may be provided with a metallic retainingring 16 at the inner periphery thereof having aVV suitable inner diameter to provide a small clearance `or openingl' between the stationary ring 16 and the rotatable shaft 12. At the outer periphery of the hearth 15 there may be provided aV plurality of openings 18 circumferentially disposed around the periphery of said hearth through which the material being treated may dropto another hearth, not shown, positioned under the hearth 15. From the foregoing it will be readily seen that the material being treated is worked from the peripheral portion of one hearth to the central portion thereof and after falling to the hearth below is worked from the central portion to the peripheral portion where it drops to the next hearth and is again worked toward the central portion and so forth, there being commonly six to nine or even more such hearths in a multiple hearth roasting furnace.

As a part of therotatable shaft 12 there may be provided an inner vertical wall 19 enclosing an inner vertical passageway 2O for an incoming cooling `medium such as air, and an outer vertical wall 21 may be pro vided for enclosing an outer vertical passageway for an outgoing cooling medium. The vertical shaft may be built in sections having flanges 23 and 24 whereby the sections may be secured together as by means of bolts 25. The bolts 25 may also hold in place a ring 26 which serves to substantially close the opening 17 and prevent the passage of ore or other material therethrough. The inner wall 19 is provided with an aperture 27 preferably circular in form, for the reception and support of a rabble arm, and similarly the wall 21 may be provided with an aperture 28 for also supporting the same rabble arm. There may be positioned around the aperture 28 an outwardly extending cylindrical flange 29 to provide more rigid support to the rabble arm extending therethrough, such flange having a radial opening 30 therein for a lock pin 31.

. For connecting the rabble arm to the vertical shaft 12, we preferably employ a socket engaging member 32 which member has at one end thereof a portion 33 having an outer cylindrical surface 34 to fit within the aperture 27Y and also having an inner cylindrical surface 35 within which is positioned a cylindrical tube 36 which is preferably formed of standard tubing such as drawn steel pipe or other suitable material which has been rolled or worked to a high degree of homogeneity. The other end of the socket engaging member 32 may be provided with an inner cylindrical surface within which is positioned a second cylindrical tube 37 which is also preferably formed of standard drawn steel tubing and which is of a somewhat greater diameter than the pipe 36. Rivets 38 hold the pipe 37 firmly in place in the member 32. Intermediate the two end portions of the socket engaging member 32 there extends a connecting portion or web 39 having preferably two or more openings therethrough such as indicated at 40. The member 32 has a recess or opening 41 adapted to receive the lock pin and maintain the socket engaging member in fixed but detachable relation to the rotatable shaft.

It will be noted that the socket engaging member 32 not only secures the tubes 36 and 37 in respect to the rotatable shaft 12 but also maintains them in spaced relation, substantially concentric with respect to each other as shown, so that there is a passage 42 between the inner and outer tubes. There is also provided a closure member 43 which member also serves to maintain the inner and outer tubes in the proper spaced relation at their outer ends. This closure member may comprise a disc-like portion with a circumferentially extending annular flange in the form of a ring or short cylindrical portion 45. The flange 45 may be secured to the outer tube 37 in any suitable manner as by rivets 46. In order to support the inner tube 36, the closure member 43 may be provided with a plurality of webs or flanges 47, the plane of said webs extending radially from the common axis of the tubes 36 and 37. The ends of the webs are reduced in diameter as by turning as indicated at 48, so that the webs may extend within the inner tube 36 and provide a support therefor. It will be noted that the passage 49 extending within the inner tube 36, is in communication with the passage 42 by means of openings 50 which lie between the webs 47 where the webs extend into the tube 36.

The flow of the cooling air is as follows. The air enters through the passageway 20 in the rotatable shaft and passes through the passage 49 to the outer end of the rabble arm and through the openings 50 to the passage 42, thence through the openings 40 into the passageway 22 from whence it is discharged, a portion of it, if desired, being used to supply the air for the combustion of the sulphur or other materials in the furnace.

In Fig. 1 there is shown a rabble tooth carrying member 51 extending longitudinally of the rabble arm to which it is secured. The method of securing such members is more clearly shown in Fig. 4 wherein a portion of the rabble carrying member is shown as being formed into an ear or flange 52 secured to the outer tube 37 by any suitable means such as rivets 53. The use of the rivets to secure these -members to the tube makes it possible to readily knock out the rivets and replace burned or broken members.

A pair of the rabble teeth carrying members 51 may be mounted on the lower surface of each of the rabble arms as indicated in F ig. 4. These two members thus provide a channelway for slidably receiving a plurality of rabble teeth of any desired and well known construction. The members 51 may comprise strips of steel rolled with the crosssection indicated, or if desired, such strips may be cast of any suitable metal capable of withstanding high temperatures. In either event the fabricated construction comprising the tubular member 37 and the two strips 51 provides a much more durable construction than has heretofore been afforded by similar constructions which have been integrally cast. As a result of the fabricated character of this construction, the rabble arm is capable of withstanding widely varying and irregular temperature conditions without warping.

liO

Furthermore, with the parts proportioned as shown, the use of thickened areas or relatively enlarged portions of cast metal, is avoided, which fact eliminates cracking and warping difficulties arising from irregular expansion of the integrally cast rabble arms as heretofore used under high temperatures.

It will be seen that the rabble arm may be readily detached as an assembled unit by rcmoving the lock pin 31 and withdrawing the arm as a whole through a door as at 54 pref" vided in the wall l1 of the furnace. Another rabble arm may be introduced through the door and secured in place by means of the lock pin 31. If desired, the socket engaging men ber 32 may be provided with lugs as at 55 to assist in guiding it into place and in securing it therein. I

In the form shown inV Fig. 2 a rsocket engaging member 32a is provided which is adapted to extend into the outer tube 37 and to have the outer tube secured thereto instead of having the outer tube extend into the socket engaging member'. An aperture Lila is provided which extends through both the outer tube 37 and the joint forming` member 32a instead of one of them only as in Fig. l. Otherwise the construction shown in Fig. 2 is very similar to that shown in F ig. l and corresponding reference characters are used for the several parts.

In the form of the invention shown in Figs. 3 and 5 the socket member may for economy of material and weight be formed as a'skeleton-like construction. A portion 56 having an outer cylindrical surface 34E to lit within the aperture 27 and having an inner cylindrical surface 35 within which is positioned the inner tube 36 is firmly secured to the inner tube as by means of rivets 57. The inner and outer tubes are maintained in proper spaced relation with respect to each other by means of a plurality of rib-like members designated generally by the reference character 58, there being four such members employed in the embodiment shown, these members being integrally cast with the portion 56. Each member 58 may comprise an inner longitudinal strip 59 adapted to rest against the tube 36 and an integrally formed outer longitudinal strip 60 adapted to rest against the tube 37. Each pair of strips 59 and 60 are oined by a reinforcing or supporting web 6l which is provided with a plurality of enlarged portions 62 provided with apertures 63 through which pass rivets 64rfor securing` the tubes 3G and 37 firmly in position. Rivets 65 may also be provided for securing the inner tube to the member 58 beyond the end of the outer tube 37.

Vith the above described constructions, it will be observed that it is possible to use relatively inexpensive standard steel tubing to make up the larger' portions of the rabble arm, special castings being necessary only for the socket and plug members and if desired for the rabble tooth carrying strips. This construction has the further advantage that socket members adapted to lit various types of conventional sockets now in use in various furnaces, may be used interchangeably with the other standard parts in making up the rabble arms. Furthermore, in view of the fabricated nature of the rabble arm assembly, if one portion of the assembly becomes worn out or broken, the remaining parts may be used? again in-a newassembly. Also, since the use' of bulky castings isavoided, the construction may be made substantially lighter in weightthan the integrally cast rabble arms heretofore used. This notI only constitutes-a saving immaterial but greatly facilitates replacement ofL worn 'outf rabble arms and the use of,V the-standard tubing renders'itt unnecessary for the user or manufacturer to keep on hand any expensive stock of'castinO's.

:':Ihe outer tubular member or body portion of the rabble armsis of course subjected to high temperatures while carryin very substantial loads and the forces app ied to this member vary greatly depending upon the character of the material being treated and upon the irregularities encountered by the rabble teeth. The steel tubing is well fitted to withstand these conditions in view of the uniform cross-section of the tubing, which eliminates internal stresses at high temperatures and in view of the homogeneous character of such tubing, the strength of which may be accurately predetermined. If desired, the tubing may be madeof steel especially adapted to withstand high temperature conditions.

While the invention has been described with respect to certain particular preferred examples which give satisfactory results, it

will be understood by those skilled in the art,

after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, in the appended claims to cover all such changes and modifications.

We claim:

1. Socket engaging means for a rabble arm of a roasting furnace having a rotatable shaft with a vertically disposed inner passageway and a vertically disposed outer passageway for an incoming and outgoing cooling medium, comprising a cylindrical portion adapted to extend into an aperture in the wall of said inner passageway and to receive at its inner end a length of standard tubing comprising a cooling fluid conduit for the rabble arm, an outer portion of said socket engaging means being adapted to be secured to the end of another length of standard tubing of greater diameter than said first-mentioned tube and also enclosing said first-mentioned tube, and means for securing said outer portion and said second-mentioned tube in an aperture of the wall of said outer passageway, the socket engaging means also having an opening therein for the passage therethrough of the cooling medium.

2. A rabble arm comprising a supporting Y tube of uniform cross section and comprising a length of standard tubing of uniform thickness and a pair'of cooperating flanged rabble-tooth supporting members disposed paralle'lV to each other and extending longitudinally of said tube and each independently riveted thereto. v v

A3. A rabble arm comprising a supporting tube of uniform cross section and comprising a length of standard tubing of uniform thickness and a pair of Cooperating flanged rabble-tooth supporting members, said members being independently formed and disposed 3 parallel to each other and extending longitudinally of Said tube and each independently secured to said tube.

In testimony whereof We have signed our names to this speoilica-tion. f y

DUDLEY BAIRD. GEORGE CONNOLLY. 

